feat(pwa): add web share target for text and images with offline queue

internal/api/server.go

@@ -308,6 +308,11 @@ func (s *Server) Router() http.Handler {
 		})
 	})
 
+	// Web Share Target fallback when service worker is not active yet: redirect to /
+	r.Post("/share-target", func(w http.ResponseWriter, r *http.Request) {
+		http.Redirect(w, r, "/", http.StatusSeeOther)
+	})
+
 	// Embedded Frontend SPA Handler
 	if s.staticFS != nil {
 		fileServer := http.FileServer(http.FS(s.staticFS))

internal/api/server_test.go

@@ -1533,6 +1533,24 @@ func TestPasswordResetFlow(t *testing.T) {
 	}
 }
 
+func TestShareTargetFallbackRedirects(t *testing.T) {
+	store, err := storage.NewStore(":memory:")
+	if err != nil {
+		t.Fatalf("NewStore: %v", err)
+	}
+	defer store.Close()
+	router := NewServer(&config.Config{Port: "8080", DatabasePath: ":memory:", JWTSecret: "test-jwt-secret-key"}, store, ws.NewHub(), nil).Router()
+	rec := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodPost, "/share-target", nil)
+	router.ServeHTTP(rec, req)
+	if rec.Code != http.StatusSeeOther {
+		t.Fatalf("expected 303 See Other, got %d", rec.Code)
+	}
+	if loc := rec.Header().Get("Location"); loc != "/" {
+		t.Fatalf("expected Location '/', got %q", loc)
+	}
+}
+
 // testSession starts a server-side session, as a login would, for tokens made directly in tests.
 func testSession(t *testing.T, store *storage.Store, userID string) string {
 	t.Helper()